Multi-channel television services via fiber optics and coaxial cables using digital compressing technique such as MPEG and digital modulation techniques such as QAM (Quadrature Amplitude Modulation) and QPSK (Quadrature Phase Shift Keying) have nowadays been developing. However, to receive signals emitted from a CATV center and to view a CATV program, it is normally necessary to use a set-top-converter (STC) composed of a MPEG decoder and a QAM demodulator.
A conventional CATV system provides subscribers with multi-channel services by the above-mentioned method. Therefore, when a subscriber wants to view CATV programs on a plurality of TV sets, he or she must provide the TV sets with separate STCs respectively. The considerable expense falls on the subscriber. Japanese Laid-open Patent Publication No. 7-59072 discloses such a unit that is attached to one CATV terminal, allowing a plurality of TV sets to receive the CATV programs. This attempt may be an improvement but still requires a large-scale CATV terminal.
As described above, any conventional CATV system requires each subscriber to provide each TV set with a CATV terminal unit or a large-scale CATV terminal to enjoy a plurality of CATV programs on a plurality of TV sets. This increases the subscriber's charge. A CATV center to which all functions of the system are concentrated may not be so flexible to manage each of areas to be covered.